Ok.

I've got a strange problem. I got my setup from LL in Dec. I had problems with the bulb starting up and flickering and Brain told me to try and leave the bulb on for a while.

The weird problem I'm having is while it's flickering my TV shows interference. It looks like a light snow pattern over the picture. This is my TV not the LCD and it is no where near the projector. Also it's on a different power line, and I tried putting an EMI filter on the projector and surge supressor too (figure it couldn't hurt). I also tried moving the projector around and it didn't seem to have any effect. I have to leave the projector one for about a hour or more before the flickering stops so I don't know if the flickering has something to do with th interference.

Some more info about the TV. It's a tube TV receiving a signal from satellite. If I play a DVD I don't get the intererence so somehow the projector (Ballast or light) is interfering with the signal, maybe some weird frequency is getting the in the cables or the powerline?

Anyone have any ideas?

Also does anyone know when the flickering bulb syndome stops? I've got about 15 hours on this bulb. The image is annoying when it's flickering.

Thanks
JDJr

My best guess would be that the cable line runing to your T.V is very near to the Power line which is hooked up to the ballast. Somewhere in the walls or attic.

Might try running a cable wire from outside at the cable box to the T.V and unhooking all the rest of the cable to see if this stops it. But even if it did a solution would be very difficult.

The only thing that changes after an hour of running is the arc stability, so it seems likely that the bulb itself (or bulb feedback to the ballast) is the source of the interference. Any arc, especially an intermittent arc can and will broadcast broadband EMI in all directions. Most electronics are sufficiently shielded to prevent outside interference from having an effect. The bulb should settle down eventually. However, in the meanwhile you could try a faraday cage. The basic idea is to surround the EMI source with grounded conductive materials. Lining the area around the bulb with metal (possibly foil, though I've heard some say it doesn't work) and grounding it should drain away the emissions from the bulb. Coaxial cable is basically an elongated faraday cage. The outer shield is grounded to protect the inner conductor from EMI. It's possible for the outer shield to be ungrounded (useless) or grounded in more than one place, which can create a ground loop (allows localized induced interference). Check your cable. If, as jonjandran suggested, your cable runs close to the PJ, moving it away could reduce or eliminate the problem. Bypassing one component at a time is a good method to help find where the EMI is entering the system.

Thanks for the fast replies. I wish I could get answers that fast to all of lifes questions.

I have a metal light box around the bulb. I tried to ground it but it didn't seem to have an effect.
I'll try to see if I can plug it in somewhere else and see if it has an effect as well as doing direct connect cable hook ups.

I had it plugged in and on for about 5 hours this morning and the flickering was still there. Does anyone have any recommendations to try to get rid of this flicker (Keep it on longer? I've got about 20 hours on the bulb and ballast)? It is definately coming from the bulb. I checked all the connections. I wire nutted everything. On a number of the wires I tried cutting the wire, restripping it and re-wire nutting it but it seems to have no effect.

JDJr

I am having a similar problem. Everything was working great for a short time and then I started to get noise on the lcd image. It only occurs once the bulb lights up (it doesn't occur when the fan is on or even when the ballast is first powered (but the bubl has yet to light).

Anyhow, I have not put in an emf on the lin to the ballast, but I am assuming that is what I am going to have to do. I'd love to hear if anyone else has any suggestions or comments.

Thanks,
Jon

Okay peeps, I finally got my bulb and ballast wired up for some testing, I fire it up and lo and behold, my wife calls down the stairs complaining that the tv picture has gone snowy. I say, "It's the winter olympics, darlin'. Of course it's snowy." ... ... :| ... Stony silence. Ahem. Anywhoo...I appear to have an EMI problem as well. The bulb was 30 feet away, and it's the standard ushio and e-ballast.

I tried several things to reduce the interference. The first was to ground the ballast enclosure. This is a test rig and my cord had no ground, so I ran a separate wire. This had little effect, but I left the ground intact anyway.

Next, I wrapped the ballast in foil and grounded it to the case. This was little better, so I removed the foil.

Next, I put the bulb in a grounded metal container (not totally sealed.) No change, container removed.

Finally, I wrapped aluminum foil around the wiring between the bulb and ballast and grounded it. This almost completely eliminated the interference. It seems that the output wiring between my ballast and bulb is acting as an antenna and broadcasting the EMI. There may be other ways to reduce the emissions. I'll do some more testing tomorrow.

Cool. I'll have to give it a try. I wonder if that out door armored wire sheeting would do the trick.
I'll have to give something a try. My bulb is still flickering and someone told me to leave it on for a long time, which is hard to do when the wife and kids are complaining about the snow so either watch a flickering projector that makes you sick or a snowy TV.

JDJr

Further testing today: I was unable to completely remove the interference this time, but considerable improvement was still to be had by shielding output wires. The interference only appears on channels 2-5 on my TV. (Antenna in the attic, no cable) Nothing else I tried today made any difference.

Shielded wire would be better. Metallic conduit and metal enclosures would probably be ideal. There may be other parts of the system that need to be shielded / grounded / isolated as well. I'll post anything new I find out.

IronGecko
Can you easily change the length of those wires and see what happens? By changing the lenght it may change their antenna characteristics and make it more difficult for the tv antenna to receive them.
Sorry I don't know enough about EMI or RF to be able to tell you to shorter or longer on the cables. I would guess shorter.

Al E

Ok I got rid of 95% of the interference by doing what Al E recommended. I moved my ballast close to the bulb so the ballast wires hook up directly to the bulb wires. I can still see very faint ghosting on my TV but not that noticeable unless you are looking for it, definately liveable. My projector doesn't look as nice with the big eballast bolted to the side but it's working so I won't sweat it. I wonder if I shielded the bulb (mogal) wire if I'd cut the interference down even more. I could probably use quad sheilded coax for my TV too and cut it down more but I'm too lazy to pull that wire through the walls.

IronGecko: Thanks for your help and insight, I wouldn't have figured it out otherwise and would have gone nuts.
Al E: Thanks for the shortening recommendation.

Now do you guys have a solution for my bulb flickering?

JDJr

I work in a lab and we do a fair amount of microscopy whereby we use a UV source to illuminate certain samples. The UV source bulbs are arc bulbs. Every once in awhile we get a bulb that simply will not produce a "stable" arc. I wonder if these projector bulbs can come up a "lemon" once in awhile too? For your sake I hope not. I put quotes around stable because no arc is truly stable within certain limits. We always try to burn-in our arc bulbs for at least a few hours on the theory that it helps produce a long-term stable arc. Don't know if that's true or black-magic-shake-a-dead-chicken sort of theory. One thing is certain for our UV bulbs at least and that is one electrode erodes and the other don't - at least not nearly so much. And when we get a dancing arc bulb we can actually watch it jump around back-and-forth between two or more spots on the eroded electrode.

Good suggestion, Al_E. Sounds like it worked for jdjr. I have pretty short wires already, but I'll cut them shorter and then try several different lengths to see what happens. Thanks!

Happy to help. I just hope it works for me when my build is complete.

Have you tried another bulb to see if that's the problem?

I haven't tried a different bulb. Brain told me to try leaving it on for a long time which I did and I still get flicker. I told him about it but haven't heard anything back yet.

JDJr

I've had grow bulbs flicker like that before.It's usually caused by impurities in the lamp's arc chamber or operating the lamp at an improper burning position.You'll get a defective new lamp every now and then.If it still flickers with a different bulb (after warm-up) then your ballast or base may be the culprit.

I was talking to a Phillips rep the other day about bulbs and burn in times, He said they should be burned in for 2 to 3 days! any thoughts on this. anyone try that long a burn in?

I do everytime I change a MH or HPS bulb.The first time I installed my projector bulb,I left it on for a week solid.I've heard it drastically increases the spectral bulb life.

A week? Yikes.
Maybe I'll try it overnight tonight and see if it has any effect.
Thanks

JDJr

Overnight will be fine for a projector.One week is recommended when you are using the lamps for vegetative growth as plants are more sensitive to the spectrum than our human eyes.